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Waskow A, Butscher D, Oberbossel G, Klöti D, Rudolf von Rohr P, Büttner-Mainik A, Drissner D, Schuppler M. Low-energy electron beam has severe impact on seedling development compared to cold atmospheric pressure plasma. Sci Rep 2021; 11:16373. [PMID: 34385534 PMCID: PMC8360967 DOI: 10.1038/s41598-021-95767-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 07/20/2021] [Indexed: 02/07/2023] Open
Abstract
Sprouts are germinated seeds that are often consumed due to their high nutritional content and health benefits. However, the conditions for germination strongly support the proliferation of present bacteria, including foodborne pathogens. Since sprouts are consumed raw or minimally processed, they are frequently linked to cases of food poisoning. Therefore, a seed decontamination method that provides efficient inactivation of microbial pathogens, while maintaining the germination capacity and quality of the seeds is in high demand. This study aimed to investigate and compare seed decontamination by cold atmospheric-pressure plasma and low-energy electron beam with respect to their impact on seed and seedling quality. The results show that both technologies provide great potential for inactivation of microorganisms on seeds, while cold plasma yielded a higher efficiency with 5 log units compared to a maximum of 3 log units after electron beam treatment. Both techniques accelerated seed germination, defined by the percentage of hypocotyl and leaf emergence at 3 days, with short plasma treatment (< 120 s) and all applied doses of electron beam treatment (8-60 kGy). However, even the lowest dose of electron beam treatment at 8 kGy in this study caused root abnormalities in seedlings, suggesting a detrimental effect on the seed tissue. Seeds treated with cold plasma had an eroded seed coat and increased seed wettability compared to electron beam treated seeds. However, these effects cannot explain the increase in the germination capacity of seeds as this was observed for both techniques. Future studies should focus on the investigation of the mechanisms causing accelerated seed germination and root abnormalities by characterizing the molecular and physiological impact of cold plasma and electron beam on seed tissue.
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Affiliation(s)
- A Waskow
- Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092, Zurich, Switzerland
- Swiss Plasma Center, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - D Butscher
- Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
- BASF Personal Care and Nutrition GmbH, Illertissen, Germany
| | - G Oberbossel
- Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
| | - D Klöti
- Competence Division for Plants and Plant Products, Seed Quality, Agroscope, Reckenholzstrasse 191, 8046, Zurich, Switzerland
| | - P Rudolf von Rohr
- Institute of Process Engineering, ETH Zurich, Sonneggstrasse 3, 8092, Zurich, Switzerland
| | - A Büttner-Mainik
- Competence Division for Plants and Plant Products, Seed Quality, Agroscope, Reckenholzstrasse 191, 8046, Zurich, Switzerland
| | - D Drissner
- Department of Life Sciences, Albstadt-Sigmaringen University, Anton-Günther-Strasse 51, 72488, Sigmaringen, Germany
| | - M Schuppler
- Institute of Food, Nutrition and Health, ETH Zurich, Schmelzbergstrasse 7, 8092, Zurich, Switzerland.
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Waskow A, Betschart J, Butscher D, Oberbossel G, Klöti D, Büttner-Mainik A, Adamcik J, von Rohr PR, Schuppler M. Characterization of Efficiency and Mechanisms of Cold Atmospheric Pressure Plasma Decontamination of Seeds for Sprout Production. Front Microbiol 2018; 9:3164. [PMID: 30619223 PMCID: PMC6305722 DOI: 10.3389/fmicb.2018.03164] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Accepted: 12/06/2018] [Indexed: 11/17/2022] Open
Abstract
The consumption of fresh fruit and vegetable products has strongly increased during the past few decades. However, inherent to all minimally processed products is the short shelf life, and the risk of foodborne diseases, which have been increasingly related to such products in many parts of the world. Because of the favorable conditions for the growth of bacteria during the germination of seeds, sprouts are a frequent source for pathogenic bacteria, thus highlighting the need for seed decontamination to reduce the risk of foodborne illness. Consequently, this study focused on cold atmospheric pressure plasma (CAPP) treatment of artificially inoculated seeds in a diffuse coplanar surface barrier discharge to determine the inactivation efficiency for relevant foodborne pathogens and fungal spores. Plasma treatment of seeds resulted in a highly efficient reduction of microorganisms on the seed surface, while preserving the germination properties of seeds, at least for moderate treatment times. To characterize the mechanisms that contribute to microbial inactivation during plasma treatment, an experimental setup was developed to separate ultraviolet light (UV) and other plasma components. The combination of bacterial viability staining with confocal laser scanning microscopy was used to investigate the impact of ozone and other reactive species on the bacterial cells in comparison to UV. Further characterization of the effect of CAPP on bacterial cells by atomic force microscopy imaging of the same Escherichia coli cells before and after treatment revealed an increase in the surface roughness of treated E. coli cells and a decrease in the average height of the cells, which suggests physical damage to the cell envelope. In conclusion, CAPP shows potential for use as a decontamination technology in the production process of sprouts, which may contribute to food safety and prolonged shelf life of the product.
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Affiliation(s)
- Alexandra Waskow
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Julian Betschart
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Denis Butscher
- Institute of Process Engineering, ETH Zurich, Zurich, Switzerland
| | - Gina Oberbossel
- Institute of Process Engineering, ETH Zurich, Zurich, Switzerland
| | | | | | - Jozef Adamcik
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | | | - Markus Schuppler
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
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